Many industrial processes require a drying step to remove water moisture or other solvents from a slurry. Such industrial processes require the balancing of a number of control variables in order to achieve or optimize toward, desired results, such as attributes of the finished product, yield over time, and energy use.
Material yield is an aspect of the drying process that is important because it is not only an indication of the performance of the process but is also a factor in determining total operational cost. Similarly, utility consumption can be a significant factor in determining the performance of the process and can be an important variable in determining total operational cost. Because utilities consumed by drying processes are often derived from non-renewable resources, the need to optimize utility consumption can be heightened.
Existing control systems for drying processes are limited in the range of input variables that are considered in order to maintain a limited set of desired outputs. For example, some systems attempt to achieve or maintain a temperature setpoint on either the inlet or outlet side of the drying process by modulating either the inlet temperature or the flow rate of raw material. This method of control does not automatically adapt to environmental variables and process variations, increasing the risk of over or under saturation of drying gasses leading to less than optimum drying conditions.
Many conventional control systems are initially set-up or baselined using assumptions made based on the design of the dryer system, and in some cases a brief pilot testing period. When the initial set-up assumptions are not revisited, dryer systems, especially in environments with highly variable ambient conditions, can fail to run efficiently. This can result in reduced yields, or unnecessary energy consumption.
Control systems that adapt to ambient conditions exist, however these do not consider the efficiency of the drying process as a whole. In addition, existing methods to determine material yield often must wait for the process to complete in order to determine the total yield.